1. Field of the Invention
The present invention relates to a liquid crystal display device, and more particularly, to a liquid crystal display device and a fabricating method thereof using liquid crystal dropping.
2. Discussion of the Related Art
Generally, a liquid crystal display (LCD) device among ultra-thin flat panel displays, each having a display screen several centimeters thickness, operates at a low voltage, thereby consuming less power as well as being portable. Therefore, the liquid crystal display device has wide applicability in various fields such as a notebook computer, a monitor, a spacecraft, an airplane, and the like.
Such a liquid crystal display device generally includes a lower substrate having thin film transistors and pixel electrodes formed thereon, an upper substrate having a black matrix layer, a color filter layer, and a common electrode formed thereon so as to confront the lower substrate, and a liquid crystal layer formed between the lower and upper substrates. An electric field is generated between the substrates by the pixel and common electrodes to drive the liquid crystal layer. Light transmittance through the liquid crystal layer is controlled through the driven liquid crystal layer to display an image.
In the above-constituted liquid crystal display, the liquid crystal layer is formed between the lower and upper substrates by vacuum injecting liquid crystals between the two bonded substrates using capillary and pressure difference. Yet, such a method takes a long time for the liquid crystal injection to reduce productivity as the substrates become wider.
In order to overcome such a problem, a new method of liquid crystal dropping has been proposed, and a method of fabricating a liquid crystal display device by liquid crystal dropping according to a related art is explained by referring to the attached drawings as follows.
FIGS. 1A to 1E illustrate perspective view of a method of fabricating a liquid crystal display device by liquid crystal dropping according to a related art.
Referring to FIG. 1A, lower and upper substrates 1 and 3 are prepared. A plurality of gate and data lines (not shown in the drawing) are formed on the lower substrate 1 to cross each other to define pixel areas, respectively. A thin film transistor (not shown in the drawing) is formed at each of the crossing points between the gate and data lines. And, a pixel electrode(not shown in the drawing) is formed in each of the pixel areas to be connected to the corresponding thin film transistor.
And, a black matrix layer is formed on the upper substrate 3 to prevent light from leaking from the areas where the gate lines, data lines, and thin film transistors are formed. A color filter layer of red, green, and blue is formed on the upper substrate 3. A common electrode is formed on the upper substrate 3.
An alignment layer is formed on at least one of the lower and upper substrates 1 and 3 for initial alignment of liquid crystals.
Referring to FIG. 1B, a main sealant 7 and a dummy sealant 8 are formed on the lower substrate 1. Liquid crystal 5 is applied onto the lower substrate 1 to form a liquid crystal layer. Spacers (not shown in the drawing) are scattered on the upper substrate 3 to maintain a cell gap.
The main sealant 7 prevents leakage of the liquid crystal as well as bonds the lower and upper substrates 1 and 3 to each other.
The dummy sealant 8 protects the main sealant 7 and is formed in a dummy area on a periphery of the main sealant 7.
Yet, when an LCD panel is formed by applying liquid crystal onto a substrate, bonding of two substrates 1 and 3 is carried out after the liquid crystal has been dropped. Hence, if a thermo-hardening sealant is used as the sealant, the sealant 7 flows out during heating and contaminates the liquid crystals 5. Therefore, the liquid crystal application uses a UV (ultraviolet) hardening sealant as the sealant.
Referring to FIG. 1C, the lower and upper substrates 1 and 3 are bonded to each other.
Referring to FIG. 1D, ultraviolet light from a UV light applier (lamp) 9 is irradiated on the sealant 7 to be hardened, whereby the lower and upper substrates 1 and 3 are bonded to each other completely.
Referring to FIG. 1E, the bonded substrate 1 and 3 are cut into cell units to complete liquid crystal cells, respectively.
FIG. 2 illustrates a perspective view for explaining a cell cutting process of cutting substrates into cell units according to a related art.
Referring to FIG. 2, a scribing line 10 is formed on surfaces of the bonded substrates 1 and 3 using a scribing device such as a diamond pen having a hardness greater than that of glass, which is commonly used as a substrate material (scribing process). Mechanical shock is then impacted on the bonded substrates 1 and 3 along the scribing line using a breaking device (breaking process), whereby a plurality of unit cells are obtained.
Instead, the scribing and breaking processes may be combined into a single process using a diamond based pen or wheel to obtain each unit cell.
Meanwhile, FIG. 2 is intended to show the cell cutting process only, rather than the cell scribing line. However, a plurality of cell scribing lines are formed substantially to remove the dummy area in the periphery when the substrates are cut into unit cells.
FIG. 3 is intended to show the cell-scribing lines in detail and illustrates a layout of a lower substrate in a liquid crystal display device having sealants 7 and 8 formed thereon for showing cell-scribing lines 10 according to a related art.
Referring to FIG. 3, the cell-scribing line 10 is overlapped with the dummy sealant 8 at predetermined areas (circles). In this case, the dummy sealant 8 has been hardened by the UV irradiation process prior to the cell cutting process.
Hence, the method of forming the unit cells by scribing and then breaking is not influenced by the hardened dummy sealant 8. However, the method of forming the unit cells by simultaneously scribing and breaking to cut the substrates into unit cells does not work well due to the hardened dummy sealant 8.
Accordingly, the present invention is directed to a liquid crystal display device and a fabricating method thereof that substantially obviate one or more problems due to limitations and disadvantages of the related art.
An advantage of the present invention is to provide a liquid crystal display device and a fabricating method thereof that facilitates a cell-cutting process in cutting cells by the simultaneous process of scribing and breaking.
Additional advantages and features of the invention will be set forth in part in the description which follows and in part will become apparent to those having ordinary skill in the art upon examination of the following or may be learned from practice of the invention. The objectives and other advantages of the invention may be realized and attained by the structure particularly pointed out in the written description and claims hereof as well as the appended drawings.
To achieve these and other advantages and in accordance with the purpose of the invention, as embodied and broadly described herein, a liquid crystal display device according to the present invention includes a substrate, a closed-end main UV-hardening sealant on the substrate, and a closed-end dummy UV-hardening sealant on a periphery of the main UV-hardening sealant, wherein a width of one portion of the closed-end dummy UV-hardening sealant overlapped with a scribing line is narrower than that of the other portions.
In another aspect of the present invention, a method of fabricating a liquid crystal display device includes preparing lower and upper substrates, forming a closed-end main UV-hardening sealant on one of the lower and upper substrates, forming a closed-end dummy UV-hardening sealant on a periphery of the main UV-hardening sealant so that a width of one portion of the UV-hardening sealant overlapped with a scribing line is narrower than that of the other portions, applying a liquid crystal on one of the lower and upper substrates, bonding the lower and upper substrates to each other, applying UV light to the bonded substrates, and cutting the bonded substrates into unit cells along the scribing line.
Namely, the present invention is characterized in that the width of the dummy UV-hardening sealant overlapped with the cell-scribing line is formed narrower to facilitate to cut the bonded substrates into the cell units.
It is to be understood that both the foregoing general description and the following detailed description of the present invention are exemplary and explanatory and are intended to provide further explanation of the invention as claimed.